Comparative Study Of Meat Qualities On Xiangxi Yellow Cattle Among Different Ages

With the improvement on the quality of life,people are getting more attention to the quality of beef whose consumption is increasing.For Xiangxi yellow cattle,there were studies on the way of fattening and breed improvement as well as reference standard for the classification of raw meat,but no systematic study on the effect of ages on its meat quality.To reveal the fine meat qualities as well as provide scientific basis for the timely slaughter on Xiangxi yellow cattle so as to promote the further development,with Angus longissimus dorsi(LT muscle)selscted as comparison under certain feeding conditions,the nutritions,processing or eating qualities,fatty acids and flavor qualities of Xiangxi yellow cattle LT muscle among the age of 6,18 and 30 months were carried on comparison and analyzed,thereby to compare the meat qualities of Xiangxi yellow cattle among different ages as well as between Xiangxi yellow cattle and Angus.The results were as follows:1.Nutrition,processing and eating quality.The researchs of Xiangxi yellow cattle LT muscle and Angus LT muscle among 6,18 and 30 months on nutrition,processing and food qualities showed that,in Xiangxi yellow cattle LT muscle,there were the highest brightness(L*)and best elasticity,lower shear force value,but lower juiciness and beef flavor scores as well as fat content,lowest redness(a*),at 6 months;There were higher juiciness and beef flavor scores,lower shear force value but lower fat content,at 18 months;There were the highest redness,higher juiciness and beef flavor scores as well as fat content,but higher shear force value,the lowest brightness and worst elasticity,at 30 months.Compared with Angus beef,Xiangxi yellow beef had higher water content and flavor score,but larger abnormal flavor,lower protein content and redness,and poor overall brightness and elasticity.2.Taste substances.There were no significant difference of taste substances on cooked Xiangxi yellow cattle LT muscle among different months,which performanced for no significant difference on total free amino acids content,umami amino acids,sweet amino acids and bitter amino acids contents as well as the monosodium glutamate equivalent concentration(EUC).Compared with Angus LT muscle whose EUC value increased significantly after cooking(100℃,5 min),there were no significant difference in EUC values between raw and cooked Xiangxi yellow cattle LT muscle.Moreover,the EUC value of cooked Xiangxi yellow cattle LT muscle was lower than that of cooked Angus LT muscle,which performanced for lower contents of umami amino acids and 5’-IMP(inosine monophosphate)as a whole on cooked Xiangxi yellow cattle LT muscle.It can be seen that the influence of ages on the taste of Xiangxi yellow beef is small;According to the EUC value changes between raw and cooked beef in two breeds,in order to obtain a better taste under cooking,Xiangxi yellow beef may need more longer cooking time than Angus beef.3.Fatty acids and volatile flavor substances.For Xiangxi yellow cattle LT muscle at different ages,the ratio of PUFA to SFA(PUFA/SFA)was higher,the contents of SFA and PUFA were lower,and the content of MUFA was the lowest,at 6 months;PUFA content was higher,PUFA/SFA was higher and close to the ideal value(≥0.4),the ratio of n-3 PUFA to n-6 PUFA(n-6/n-3)was higher and close to the optimal range(4:1～6:1),SFA content was lower,at 18 months;MUFA content was the highest,SFA content was higher,PUFA content as well as PUFA/SFA and n-6/n-3 were lower,at 30 months.Compared with Angus LT muscle,Xiangxi yellow cattle LT muscle has a higher PUFA content but lower n-6/n-3.A total of 44 volatile substances were detected in Xiangxi yellow cattle LT muscle and Angus LT muscle,including 6 alcohols,12 aldehydes,2 ketones,4 acids,2 esters,14 hydrocarbons,2 heterocyclic compounds as well as 2,4-2-tert-butylphenol and n-octyl ether.For Xiangxi yellow cattle LT muscle at different ages,the contents of volatile flavor substances were higher with more stronger odour at 18,30 months.Compared with Angus beef,Xiangxi yellow beef has higher contents of volatile flavor substances with more stronger odour.4.Conclusion.Through the comparison of the nutrition,processing and edible qualities,fatty acids and volatile substances between Xiangxi yellow beef and Angus beef,Xiangxi yellow beef has lower protein content and poorer elasticity,but higher polyunsaturated fatty acid content and stronger odour.In Xiangxi yellow cattle at different months,the flavor of18 months was significantly improved compared with that of 6 months;The color of 30 months was the best,but the flavor of 30 months has no obvious advantage compared with that of 18 months,and the tenderness under 30 months is poorer.Thus,with the growth rate slowed down and the return rate of feed decreased in the later stage of cattle growth,it was preliminarily determined that the slaughter of Xiangxi yellow cattle at the age of 18 months was appropriate.